Tracked excavator ground preparation is the most common system for conifer restocking in the Forestry Commission (FC). Based on a Technical Development survey of the FC in 2007/2008, just less than 90% of the programme was completed by tracked excavators. Scarification by disc scarifiers has been recommended (FC literature) as a potentially cheaper and less intrusive cultivation system than some forms of tracked excavator site preparation. This scoping study on a site in north England collected data on scarifier performance and cross references results with OGB 4 criteria.

In this example, for ‘on the shoulder’ planting the average spacing between rows is 2.14 m and the average spacing within rows would have to be 1.73 m to achieve 2700 trees per hectare. If an average spacing of 2.14 m between rows is acceptable then scarification on this site would meet OGB 4 requirements.

On drier sites, practitioners can plant in the furrow and an average within machine pass row spacing of 1.7 m was achieved for the furrows on the narrowest setting. With furrow planting, a 1.9 m by 1.9 m spacing will be more achievable. The outputs of 0.46 to 0.51 hectare per hour recorded at Rothbury for 100 m runs with two way working (i.e. good access) could be judged as conservative when compared to Technical Development Branch Report 6/93: Timberjack 450B/Donaren 280 Scarifier. The lower outputs in this scoping study may reflect the increased rigour of OGB 4.

It is recommended that:

Disc scarification is considered for new planting and restocking and that between row spacing is closely monitored for OGB 4 compliance.

Information was collected on the Clark rotary plough preparing ground for native woodland establishment by provision of mounds either side of a ploughed furrow. A similar, but larger plough (producing furrows at wider spacing) was originally built by William Clark and Sons, Parkgate in 1978 which was designed for establishing commercial conifer forests.

An output of 0.70 ha/shr was recorded for a cost of £36.00/ha which excludes site movement and subsistence costs.

The current plough is producing a smaller mound volume than recommended by Forestry Commission Bulletin 119 Cultivation of Soils for Forestry. Smaller mounds will generally require more attention during water management, planting and weed control.

Further development work needs to be carried out to ensure the desired mound density and uniformity can be achieved to meet OGB 4 specifications for commercial conifer woodlands.

Managers should consider the rotary plough as an option for use in native woodland establishment. The current design can be adversely affected by wetter conditions and dense vegetation growth and its use should be restricted to better drained soils and/or less fertile sites.

The Forestry Commission uses over 100 000 co-extruded plastic bags for the storage and transport of millions of trees each year. Recent Government initiatives on recycling have prompted an awareness to explore alternatives to current management systems, which rely on disposal of single, use bags. Co-extruded bags are made from polythene, which is a thermoplastic polymer.

Technical Development was asked to investigate the disposal of co-extruded bags and to identify other handling systems.

When investigating other systems, paper bag and cardboard box based alternatives were discovered. A small trial showed:

There were conflicting reports on the capabilities of the paper bags.

Cardboard boxes are more robust than bags and can be manufactured to required specifications.

A range of clearfelled upland sites on gley soils, aged from one to five years post felling, were surveyed in 2007, 2008 and 2009 to determine patterns of revegetation and any changes in ground conditions. Data were analysed using the Ecological Site Classification (ESC) to determine soil moisture and soil nutrient status, while statistical analysis was used to identify relationships between site age and vegetation growth and community structure.

Results demonstrated a rapid increase in site biomass with increasing site age across all site types surveyed. A significant change in vegetation type was also apparent over time.

On those sites which had been cultivated since the first survey, the effects of cultivation on overall weed growth were relatively small. Continued monitoring of cultivated sites will be necessary to confirm the pattern of revegetation on prepared planting positions.

Provision for control of predominantly grassy weeds should be made for sites planted more than two years after felling, within the range of soil and climatic conditions surveyed. Up to date herbicide application costs should be compared with the costs of insecticide protection of trees and/or biological control of Hylobius to enable a true comparison of the various options.

There is a need to identify the best methods for applying Forestry Commission guidelines for creating new native woodland by direct seeding at the farm scale, using existing or adapted agricultural equipment and techniques. Trials were carried out at Harper Adams University College over three years, and results indicated that commonly available equipment could be used to sow a range of tree seeds at the recommended rates and depth.

The third phase of trial, involving the sowing and incorporation of pre-treated ash seed, was carried out as a student project. The students’ report concluded that the machinery trialled in this project could be used to distribute untreated ash seed without modification, but that handling pretreated ash seed was more problematic.

The addition of an airflow and use of both fine and coarse carrier media improved the flow of treated seed, but further work would be required to develop a reliable system for sowing pretreated ash. The results of germination testing suggest that the system developed so far has no detrimental effect on seed germinability.

This study shows that there are not many mechanised options for GB forestry conditions. Mechanical weeding machinery is more suited to new planting schemes on farms and short rotation coppice (SRC). Due to the physical nature of the machinery and the need to minimise tree damage, the area immediately around each tree is left uncultivated and the surrounding vegetation competes with the trees for soil moisture and nutrients.

The Neem tree (Azadirachta indica) is native to India and is also grown in Africa and parts of America for the production of neem nuts to produce an oil rich natural compound. This has an ingredient Azadirachtin, which triggers various behavioural responses in insects.

Laboratory and field experiments have shown the efficacy of Neem oil to be inconclusive.

Neem oil does not have approval as a plant protection product in the UK.

Given the low toxicity and potential efficacy of azadirachtin, neem oil should be included as a comparative treatment alongside existing approved insecticides and experiments should be planned to investigate the crop tolerance and efficacy of Neem oil as an alternative to alpha cypermethrin and cypermethrin.

The European Framework Directive for the sustainable use of pesticides requires member states of the European Union to establish certificate systems for the inspection of pesticide application equipment. No date has yet been set for the development of such a scheme in the UK, but it is likely to be put in place within the next 5 years.

A voluntary system has been established in the UK by the National Sprayer Testing Scheme. Although primarily targeted at mechanised agricultural operations the scheme is also open to professional users of knapsack sprayers.

This report describes a voluntary inspection scheme, based on the National Sprayer Testing Scheme, that could be adopted by the Forestry Commission.

Technical Development carried out a desk study to review tree planting machine use in Great Britain. The study shows very little development in terms of machinery and operating systems since the 1990s.

The expected 90s surge of new planting and short rotation coppice planting failed to materialise and most machines disappeared leaving behind few contractors to carry out what little work was available.

A fall in the manual planting workforce has increased the call for mechanisation in other parts of Europe and further afield.

The results of this evaluation indicate that operations using a tilting base tracked excavator for ground preparation and brash mat mulching can be carried out on steep terrain.

The availability of a brash mat for the machine to travel on is important, this trial has indicated that a well produced and maintained route enabled the machine to travel over the site on slopes up to 55%. The brash also assisted traction and stability when the machine negotiated a side slope. On routes where the ground was less steep, 30–40%, the machine was able to move with limited brash however manoeuvring and traction were compromised with the tracks sliding through the shallow brash mat into the soil level.

The machine did not perform well without brash or on a side slope; it was difficult to control and steer and only wanted to move in a straight line. The 32 tonne weight of the machine was a major factor affecting its manoeuvrability.

Ground preparation using hinge mounding produced mound densities of between 2766 and 2930 mounds per hectare. Outputs from the operation were 0.081 ha/shr. The costs were £957/ha.

The FECON BullHog BH80 mulcher was tested on a selection of brash mat types.

Assessment of the treated area on a thick, dense and compacted brash mat indicated that it had not been fully penetrated or mulched, low lying material close to the ground was not mulched, and branches and woody debris formed a barrier to the planting position. The output from this treatment was 0.008ha/shr and a cost of £1834/ha.

What's of interest

OutDoor WorkshopOriginally produced for delegates attending the respective workshops.

Forestry Commission Project ReportSummaries are given on this page. Depending on the status or the reports, additional information may be made available on request to the contact name shown against the respective summary.